It's from the construction site. Along with the union badge that he had, with the keys towards the Excavator, he managed. It was all that that made him the man that he was before becoming a reincarnated golem. His alcoholism having to be rehabilitated.
With its design of carbon along with the hole, that'd help out. Standard issue, black plastic flips.
On the markings there is the union mark he had placed to make it so. It was almost prideful, and it's shared among several other hard-hats.
Sitting there for many years. It's been removed from and inside an evidence locker.